Dumbbell with quick release bolt

ABSTRACT

A dumbbell including a tubular handle with a thread on the inside surface of the tube. A straight groove that cuts through the internal thread is also formed on the inside surface of the tubular handle. A stop plate is mounted on each end of the tubular handle. A pair of retainers are provided, each retainer being a shaft with a retainer plate on one end. Each shaft has a partial thread on its outside surface extending the length of the respective shaft. A weight plate stack is mounted on the shaft and the shaft is securely inserted into the tubular handle by aligning the partial thread with the groove, sliding the shaft through openings in the weight plates into the tubular handle, then rotating each shaft to where the partial thread on the shaft engages the interior thread of the tubular handle.

This invention relates to dumbbells and particularly to a set ofdumbbells that feature quick removal of plates with a quickly removableretaining bolt for changing the weight of the dumbbell as well asquickly changing to a longer retaining bolt for operating in a greaterweight range when required.

BACK GROUND AND INFORMATION DISCOSURE

A dumbbell set is a pair of weights, one dumbbell in each hand, withwhich various exercises are performed such as curls, overhead press,supine press, and just about any motion holding the weight and movingthe arms.

The original dumbbell, before the turn of the last century came into useconsisting of a bar about twelve inches long to which were secured(plates) weights and collars for securing the weights. According to thisarrangement, each bar had one pair of collars, centrally located on thebar and spaced from one another to permit grasping the center of the barwith one hand, with replaceable weights located on both ends of the barheld by retaining collars. The weights are typically cast iron plateshaving central apertures through which the handle is inserted. Theweight is selected by choosing plates having appropriate thickness anddiameter.

For safety sake, it is important that that the collars be secured veryreliably to the bar. This is because the exercises generally involveswinging the dumbbells in a manner such that the weights could be flungoff the handles in unpredictable directions if the collars become looseand separate during the exercise.

For many years, each collar has been a metal ring that slides onto theend of the bar. The ring is secured to the bar by a set bolt screwedthrough the metal ring against the bar. The head of the bolt istypically a “tee” that permits the user to apply greater torque whenscrewing the bolt against the bar to replace the plates.

This arrangement is not entirely reliable. The set bolts occasionallyloosen regardless of the effort to tighten the bolt. At the least, thisis an annoying interruption of the exercise.

Another persistent annoyance is the requirement to change the weight ofeach exercise. This requires loosening the bolt, sliding the ring offthe handle, adding or subtracting the required weight, and then slidingand securing the ring back onto the handle.

Another problem with this design is the extension of the bar end andcollar past the plates which interferes with the users ability to restthe dumbbells on his knees with the dumbbell handles orientedvertically.

U.S. Pat. No. 6,039,678 to Dawson discloses a dumbbell including ahandle being a tube with an internal thread and a pair of fixed “stop”plates, one “stop” plate mounted on one end of the handle and the other“stop” plate mounted on the other end of the handle. A pair of threadedshafts is provided. Each shaft has a “retainer” plate on one end. Theopposite end is screwed into a respective end of the threaded tube.

A stack of weight plates is mounted on each shaft. Each of the weightplates has a slot extending from a central opening to the edge of theplate so that the plate can “straddle” the tube. The weight plate ismounted on the respective shaft by unscrewing the shaft sufficiently(partially) out of the handle to permit sliding the shaft through theslot and then tightening the stack of weights between the respectiveretaining plate and stop plate. Each weight plate has a convex dimple inits surface which engages a concave dimple in a neighboring weightplate. When the stack is tightly clamped between the stop plate andretainer plate, the engaging dimples prevent slippage of the weightplate off the shaft. However, if the stack becomes loose whileperforming the exercise, the weight plate can slip off the handle.

Another problem is that, the stop plate is susceptible to being bentwhen the dumbbell is dropped so that the dimples no longer secure thestack to the handle.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a dumbbell set that enablesa user to change weight with greater speed and convenience than dumbbellsets of the present art.

It is another object that the dumbbell set be less susceptible to damagethan sets of the present art.

It is another object to display the weight on the dumbbell.

This invention is directed toward a dumbbell comprising a handle being atube about seven inches long. The interior surface of the tube isthreaded. A “stop” plate, preferably rectangular, is concntrically andperpendicularly mounted opposite another stop plate on the other end ofthe tube.

Each stop plate has a centrally located aperture providing access forinserting a retainer shaft into each end of the tube.

Each retainer shaft has a (preferably square) retainer plate mountedconcentrically and perpendicularly onto an end of the retainer shaft.The retainer shaft has a diameter selected to be a slideable fit intothe tube.

The interior threaded surface of the tube has a straight grooveextending from one end of the tube to the opposite end. The shaft has anexternal partial thread on one side extending along the length of theshaft. The thread has a width selected to permit sliding the shaft intothe tube when the partial thread is aligned with the groove. Afterinserting the shaft into the tube, the disk handle is turned so that thepartial thread on the shaft engages the thread on the interior surfaceof the tube.

The retainer is thereby locked into position relative to the handle.Weight plates mounted on the retainer shave are secured between theretainer plate and the stop plate.

The thickness of each weight plate is an integer multiple of the pitchof the partial thread (threads per inch). Therefore the user canimmediately determine that the retainer is completely secured by amarking on the retainer plate indicating that the orientation of theretainer plate.

Indicia on surface of the shaft which is visible through a pair ofapertures in the handle provide a convenient indication of the amount ofweight on the dumbbell.

The foregoing summary has highlighted features, aspects and advantagesof the present invention. The invention is further explained by thefollowing description of what I presently believe to be the best modefor carrying out the invention illustrated by drawings to which areappended claims which define the scope of the invention.

BRIEF DESCRITION OF THE DRAWINGS

FIG. 1 shows the assembled dumbbell of this invention.

FIG. 2 shows an exploded view of the dumbbell.

FIG. 3 shows the dumbbell plate with a slated edge.

FIG. 4A is a perspective view showing an end of the retainer with thepartial thread.

FIG. 4B is an end view of the dumbbell showing the stop plate, thegroove and the thread on the interior surface of the tube.

FIG. 5 shows the retainer poised for insertion into the tube.

FIG. 6 shows the scale for indicating weight of the loaded dumbbell.

FIG. 7 shows a composite retainer plate.

DESCRI[TION OF A BEST MODE

Turning now to a discussion of the drawings, FIG. 1 shows a plan view ofa pair of the dumbbells 10 of this invention. FIG. 2 is an exploded viewof one dumbbell 10 shown in FIG. 1.

There are shown a dumbbell handle being a tube 12 with a thread 14 on aninternal surface that extends from one end of tube 12 to the other end.As shown to best advantage in the end view of the tube 12 in FIG. 4B, agroove 16 is formed in the internal surface of tube 12 that extends fromone end of tube 12 to the other end.

A square “stop” plate 18 is mounted perpendicularly and concentricallyon each end of the tube 12.

A retainer 20 is shown being a retainer plate 22 mounted concentricallyand perpendicularly on one end of a shaft 24. The shaft 24 ha a partialthread 26 on one side of its surface extending the entire length ofshaft 24.

As shown in FIG. 5, the shaft 24 with it partial thread 26 with groove16 is poised for slideably telescoping the shaft 24 into the tube 12.

Weight plates 30 (shown in FIG. 1 and to better advantage in FIG. 3) arepreferably square and have a central aperture 32.

The stack of weight plates are mounted onto the dumbbell 10 by insertingthe shaft 24 through aperture 32, aligning the partial thread 26 withgroove 16 and then sliding the shaft 24 into the tube 12. The stack ofweights is secured by rotating the retainer plate 22 so that the partialthread 26 on the shaft 24 engages the internal thread 16 of the tube 12thereby securing the stack of weight plates 30 between the retainerplate 22 and stop plate 18.

The thickness of each weight plate 30 is a multiple integral of thepitch of the partial thread 26 so that, when the stack of weights issecured between the disk 22 and the stop plate 18, the disk will alwayshave the same orientation regardless of how many weight plates 30 aremounted on the dumbbell 10.

FIGS. 5 and 6 show an embodiment in which the edge 36 of each weightplate 30 is slanted.

The slanted 36 enables the user to lean the weight plates against thestop plate 18 to facilitate inserting the shaft into the tube 12.

FIG. 6 shows another embodiment according to which the user caninstantaneously determine the weight of the stack on the dumbbell 10.The weight plates 30 are preferably square. Eaxh plate has a thicknessequal to a multiple of a common thickness. The stack of weight plates 30are shown in phantom in FIG. 6. A scale 32 is engraved on the shaft 24and extends from one end to the other end of the shaft 24.

A hole 34 is formed in the tube 12 next to the stop plate and positionedso that, when the shaft is screwed into the tube sufficiently far tosecure the weight plates 30 on the dumbbell 10, the weight of thedumhbell 10 with stack 30 is indicated by the scale number on the shaft24 that is visible through the hole in the tube 12.

FIG. 7 shows another embodiment in which the retainer plate on theretainer 20 is a composite of a thick rubber 40 laminated to a metalplate 42. The advantage of the rubber lamination 40 is that, when theretainer is screwed against the weight, the retainer is effectively“spring loaded” against the weight plate 30 so that loosening of theretainer plate 40 on the shaft 24 is prevented.

The dumbbell of this invention has several advantages over dumbbells ofthe prior art.

One advantage is the ease with which the weight is changed together withthe security of complete engagement of the weight plate on the shaft.

Another advantage is the angled edges of each weight plate so thatplates lean together and alignment of the holes through the plates ismaintained. Insertion of the shaft through the aligned holes isfacilitated for loading the plates onto the shaft.

Another advantage is convenient reading of the weight loaded on thehandle through the aperture in the handle.

Another advantage provided by the rubber laminated retainer disk isthat, by screwing the shaft to where the rubber on the retainer plate isforced against the stack of weights, the compressed rubber biasesagainst loosening of the retainer plate.

Variations of this invention contemplated after reading thespecification and studying the drawings may be contemplated that arewithin the scope of the invention.

For example, the entire surface of the retainer plate may be coated witha protective rubber coating. The rubber coating on the retainer platereduces the danger associated with conventional dumbbells where the endof the handle extends out of the end of the stack of weights, Theextending handle of the conventional dumbbell poses the danger ofgouging the thigh of the user as he swings the dumbbell.

I therefore wish to define the scope of my invention by the appendedclaims.

1. A dumbbell which comprises: a handle tube having an interior surface;said interior surface having an interior thread extending from one endto the opposite end of the handle tube; a pair of stop plates; each saidstop plate having an aperture centrally located in each stop plate,respectively; one of said stop plates mounted perpendicularly andconcentrically on one end of said handle tube and another one of saidstop plates mounted perpendicularly on an opposite end of said handletube; said interior surface having a straight groove extending from oneend to an opposite end of said handle tube; a pair of shafts, one shaftfor each end of said handle tube; each shaft having a retainer platemounted perpendicularly and concentrically on one end of said eachshaft; each shaft having a linear partial thread mounted on a surface ofsaid each shaft; said partial thread extending from one end to anopposite end of said shaft, respectively; one plurality of weightplates, each said weight plate having a centically located aperture topermit mounting said one plurality of weight plates on one said shaft byinserting said shaft through said apertures; and another plurality ofweight plates, each said weight plate having a centically locatedaperture to permit mounting said another plurality of weight plates onanother one of said pair of shafts by inserting said another one shaftthrough said apertures in said another plurality of weight plates; eachsaid shaft having a diameter and said partial thread having a pitch andwidth and said interior thread having a pitch and said groove having awidth all arranged in operable combination to permit aligning saidpartial thread with said groove then telescoping each said shaft into aninterior at respective ends of said tube, then turning said shaft toengage said partial thread on said shaft with said partial threadwhereby said shaft is detachably secured to said handle tube and saidone and another plurality of weights are secured between said one andanother retainer and stop plates, respectively.
 2. The dumbbell of claim1 wherein all of said weight plates have a common thickness from one endof said aperture to an opposite end of said aperture.
 3. The dumbbell ofclaim 2 wherein all of said weight plates have a thickness from one endof said aperture to an opposite end of said aperture equal to a multipleof a common thickness.
 4. The dumbbell of claim 3 wherein said commonthickness is a multiple of said pitch of said internal thread.
 5. Thedumbbell of claim 4 wherein: each said shaft has a linear scale ofindicia representing distance formed in a straight line from adjacentsaid respective retainer plate to an opposite end of said respectiveshaft; said handle tube has a pair of openings in a side of said handletube, one said opening proximal to one said stop plate and another saidopening proximal to said other stop plate arranged in operablecombination with said shafts screwed into respective ends of said handletube to indicate an amount of weight of said pluralities of weightplates retained between said retainer plate and said respective stopplate.
 6. The dumbbell of claim 1 wherein at least one of said retainerplates is a composite plate an elastomeric layer laminated to a metalplate.
 7. The dumbbell of claim 3 wherein each said weight plate has anedge that is oblique to a centerline of said respective weight plate. 8.A dumbbell which comprises: a handle tube having an interior surface:said interior surface having an interior thread extending from one endto an opposite end of said handle tube; a pair of stop plates; each saidstop plate having an aperture centrally located in said respective stopplate; one of said stop plates mounted perpendicularly andconcentrically on one end of said handle tube and another and anotherone of said stop plates mounted perpendicularly and concentrically on anopposite end of said handle tube; said interior surface having astraight groove extending from one end to an opposite end of said handletube; a pair of shafts, one shaft for each end of said handle tube; eachshaft having a retainer plate mounted perpendicularly on one end of saidrespective shaft; each shaft having a linear partial thread mounted on asurface of said shaft; said partial thread extending from one end to anopposite end of said shaft; said shaft having a diameter and saidpartial thread having a pitch and width and said handle tube having aninterior diameter and said interior diameter thread having a pitch andsaid groove having a width all arranged in operable combination topermit aligning said partial thread with said groove then telescopingsaid shaft into an interior of said tube, then turning said shaft toengage sad partial thread on said shaft with said thread on saidinterior surface of said tube whereby said shaft is detachably securedin said handle tube; one plurality of weight plates with aperturescentrally located in each weight plate for mounting on one end of saidhandle tube by inserting one said shaft through said apertures andscrewing into said one end of said handle tube; and another plurality ofweight plates with apertures in each weight plate for mounting onanother end of said handle tube by inserting another said shaft throughsaid apertures and screwing into said another end of said handle tube;each of said weight plates having a thickness that is a multiple of acommon thickness from one end of said aperture to an opposite end ofsaid aperture; said common thickness being a multiple of said pitch ofsaid internal thread; each said shaft having a linear scale of indiciarepresenting distance formed in a straight line from adjacent saidrespective retainer plate to an opposite end of said respective shaft;said handle tube having a pair of side openings in a side of said handletube, one said opening proximal to one stop plate and another saidopening proximal to said other stop plate arranged in operablecombination with said shafts screwed into respective ends of said handletube to indicate an amount of weight of said pluralities of said weightplates retained between said retainer plate and said respective stopplate; at least one of said retainer plates being a composite plate ofand elastomeric layer laminated to a metal plate; each said weight platehaving an edge that is oblique to a centerline of said respective weightplate.